UAB „Buiteka LT“ manufactures NVB/AF  non-reagent biological wastewater treatment plants for the treatment of domestic and chemically related wastewater up to the currently valid wastewater treatment standards specified in the “Wastewater Management Regulation” approved by Order No D1-236 of the Minister of Environment of 17 May 2006 (2019 edition).

Characteristics of the proposed equipment:

• the device is environmentally friendly, as the aerobic microorganisms biodegrade wastewater pollutants, do not emit an unpleasant odor, and the treated wastewater is harmless and odorless;
• The device works quietly as it has no moving parts.
• It is made of fiberglass; all main external and internal structural elements are durable and corrosion-resistant;
• The unit consists of one tank; no additional pre-cleaning and additional cleaning facilities are required;
• Aeration is provided with the help of a blower.

The wastewater enters the aeration chamber (4) of the unit by the self-flow through the inlet pipe (5); it is mixed there with activated sludge during intensive aeration. The air supplied by the blower is directed by a supply pipe to the lower part of the aeration chamber, where it rises through the diffuser in small bubbles, saturating the mixture of oxygen-treated wastewater and activated sludge. Biological wastewater treatment takes place in the aeration chamber: the microorganisms in the activated sludge break down organic pollutants into simpler chemical compounds, such as nitrites, nitrates, most of which are subsequently oxidized to carbon dioxide and water.

The mixture of treated wastewater and activated sludge enters the secondary precipitator (9) through the horizontal overflow edge from the aeration chamber (4). The treated effluent clarified in the precipitator flows through the toothed edge and enters the annular duct and flows out of the unit through the effluent pipe (11). The activated sludge in the mixture settles to the bottom of the precipitator under the influence of gravity and slides to the bottom of the aeration tank. The activated sludge is lifted from the bottom by a stream of air and mixed in an aeration chamber (4).

The aeration chamber is equipped with an airlift (10), which is periodically switched on, thus creating aeration, mixing and idle modes in the unit. Airlift does not work in aeration mode. The mixing mode is ensured by opening the valve. During this process, the sludge from the bottom of the aeration chamber is lifted to the top of the aeration chamber, as a result of which nitrogen compounds are removed from the wastewater. Air bubbles rising to the surface of the secondary precipitator cloud the crust of the leached sludge and the sludge settles to the bottom of the unit. During idle mode, the blower is turned off, and the conditions for the release of carbon dioxide from the wastewater are created.

These modes are automatically controlled by a special controller installed in the blower well. The controller has the following modes: guest - magnified; holiday - reduced wastewater load of the device.

Contamination of treated wastewater with nutrients (nitrogen and phosphorus compounds) in treatment plants with a capacity of up to 5.0 m³ / day from 1 November 2019 is standardized and must not exceed N_B <25 mg / l and P_B <5, 0 mg / l. The nutrients are removed here successfully combining the nitrification and denitrification processes in the plant, leaving them as needed to support the synthesis of activated sludge microorganism cells and their vital activity.

The efficiency of the plant is increased by concentrating the activated sludge by means of an “attached microflora”, i. by placing an appropriate charge in the aeration tank (8).

The efficiency of the plant is increased by concentrating the activated sludge by means of an “attached microflora”, i.e., by placing an appropriate charge in the aeration tank (8).